[taskbar]The opening app didn't show in taskbar sometimes.

[kyt]

[Machine]
Dell Vostro 3900
  [Version]
18.04 daily 20180412 +
kylin-video_1.1.6-0ubuntu2、
youker-assistant_3.0.4、
Ukui-control-center_1.1.2-0ubuntu1

  [Details]
[taskbar]The opening app didn't show in taskbar sometimes.
【概率】任务栏，偶发出现打开的程序在任务栏中不显示 -- 32位系统上出现，刘敏发现的

  [Test Case]
1. Open an app and check the taskbar
Expected Result:Passed
Actual Result:The opening app didn't show in taskbar sometimes.

[Xu Jianhong (jianhong)]

This bug was fixed in bionic-final 0425 version

[kyt (952456204-6)]

the bug exists in bionic-final 20180427 enhanced

[Harry Sheng (harrysheng00)]

                          ./+o+- harry@hp-dv3
                  yyyyy- -yyyyyy+ OS: Ubuntu 18.04 bionic
               ://+//////-yyyyyyo Kernel: i686 Linux 4.15.0-29-generic
           .++ .:/++++++/-.+sss/` Uptime: 2h 56m
         .:++o: /++++++++/:--:/- Packages: 1947
        o:+o+:++.`..```.-/oo+++++/ Shell: bash 4.4.19
       .:+o:+o/. `+sssoo+/ Resolution: 1680x1050
  .++/+:+oo+o:` /sssooo. DE: GNOME
 /+++//+:`oo+o /::--:. WM: Ukwm
 \+/+o+++`o++o ++////. GTK Theme: Adwaita [GTK2/3]
  .++.o+++oo+:` /dddhhh. Icon Theme: Adwaita
       .+.o+oo:. `oddhhhh+ Font: Cantarell 11
        \+.++o+o``-````.:ohdhhhhh+ CPU: Intel Core2 Duo T6500 @ 2x 2.1GHz [67.0°C]
         `:o+++ `ohhhhhhhhyo++os: GPU: intel
           .o:`.syhhhhhhh/.oo++o` RAM: 2807MiB / 3943MiB
               /osyyyyyyo++ooo+++/
                   ````` +oo+++o\:
                          `oo++.

None of my open application has an icon on the launcher bar, except two icons for filemanager and firefox even though I did not open anyone of them.

[handsome_feng (feng-kylin)]

Hi, Harry Sheng,
  I think this is because your "windows list" applet has been hidden, and you can right click the panel and choose "reset the panel".